Thyroid Function
Normal range 0.8-1.8 ng/dL (10-23 pmol/L SI). Specimen: Serum.
Also known as: FT4.
Combined adult band. LabVals does not publish separate men's, women's, or pediatric ranges for Free Thyroxine (Free T4); those can be narrower than the band shown.
| Specimen | Serum |
|---|---|
| Conventional range | 0.8-1.8 ng/dL |
| SI range | 10-23 pmol/L |
| Conversion factor | ×12.87 (conventional → SI) |
| Panel | Thyroid Function |
Convert any Free Thyroxine (Free T4) result between units on the unit converter.
The standard teaching reference range for Free Thyroxine (Free T4) is 0.8-1.8 ng/dL in conventional units, or 10-23 pmol/L in SI units. This value is measured in serum.
Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population - always use the range printed on the actual result.
Above the range
What causes a high Free Thyroxine (Free T4)? Read as its own page
Below the range
What causes a low Free Thyroxine (Free T4)? Read as its own page
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